Your experience reinforces that it is not an either-or situation.
Sorry to hear of teacher sarcasm, as sarcasm is detrimental.
Unfortunately teachers who are unsupportive are fairly common.
DYS membership is not necessarily a "recognition" in that it is not an earned award, and is not based on merit, but rather is a source of potential assistance in connecting with support/help for those with a rare intellectual profile.
Regarding the validity of advice:
Wherever you are, it is beneficial to become familiar with your applicable education laws and also your school policies.